Method and system for using vocorder rate determination for high quality CDMA voice transmission

ABSTRACT

In a CDMA based wireless digital communications system, a CDMA communications station. A CDMA communications station includes a signal encoder adapted to encode signaling information into a signaling packet. A voice encoder is also included to encode voice information at a variable data rate and process the voice information into a voice packet. A multiplexer is coupled to receive the voice packet from the voice encoder and coupled to receive the signaling packet from the signal encoder. The multiplexer combines the voice packet and the signaling packet into a traffic frame. A transmitter is coupled to the multiplexer for transmitting the traffic frame as received from the multiplexer. The multiplexer is further coupled to receive an early data rate indication from the voice encoder such that the multiplexer is able to preconfigure the traffic frame for the variable data rate voice packet to be delivered once the processing of the voice encoder is complete. This allows the traffic frame to be sent to the transmitter for transmission immediately upon reception of the voice packet from the voice encoder, thereby reducing the latency of the digital communications system.

TECHNICAL FIELD

The present invention relates generally to digital information systems.More particularly, the present invention relates to code divisionmultiple access (CDMA) based transmission and reception systems for lowlatency, high-quality, voice applications.

BACKGROUND ART

The transmission of digital information and data between systems hasbecome an essential part of commonly used systems. With such systems,information content is transmitted and received in digital form asopposed to analog form. The transmission of voice information acrosslong distances has long been associated with well known analogtransmission techniques. These techniques include, for example, thetraditional plain old telephone system (POTS) network, conventionalwireless VHF/UHF two-way communications systems, and the like. Themodern digital form of communication and signal processing techniquesoffer numerous advantages and are rapidly replacing the traditionalmeans. In most applications, the user has no perception of the digitalnature of the information being received. CDMA based digital cellularsystems are among the most rapidly growing of the modern forms ofdigital communications.

Prior art FIG. 1 shows a CDMA digital cellular system 100. System 100typically includes many hundreds of mobile cellular telephones (e.g.,“cell phones”) communicatively coupled to a base station in a geographicarea. FIG. 1 depicts a single such base station 104 and a single cellphone 102. The transmission system uses an RF communications channel 106to link the base station 104 with the cell phone 102.

In typical applications, many hundreds of cell phones share thecommunications link 106 to the geographical area's base station 104.Digital signal processing techniques allow the efficient use of thelimited communications channel bandwidth by the multiple cell phones.CDMA is, in part, a signal processing technique which provides for theefficient multiplexing of voice and other data into discrete time andfrequency based packets of information for transmission between each ofa plurality of cell phones (e.g., cell phone 102) and the shared basestation 104.

Although the CDMA algorithms are very efficient, the bandwidth of thecommunications channel 106 is finite. As with other digitalcommunications systems, there are times when two-way communicationsusing system 100 will suffer some amount of signal degradation duringthe transmission from the originating device to the receiving device.

This degradation can have many causes. For example, bad weatherconditions may reduce the effective bandwidth available forcommunications channel 106. As another example, system 100 may at timesrequire the transmission of large amounts of signaling and callmaintenance data in addition to the voice traffic. In both these cases,the available bandwidth for transmitting voice information may at timesfall below some optimal level. This degradation often results in theloss of some voice information, some distortion in the voice signal, orsome noticeable noise in the received signal (e.g., as in the case of awireless telephone). Generally, the more significant the loss ofinformation at the receiving device, the more objectionable performanceof the communications system.

Hence, the basic cause of the degradation is the fact that, at certaintimes, there exists more voice information than available bandwidth fortransmission of the voice information, causing system 100 to reduce(e.g., throw away) some amount of voice information to fit within theavailable bandwidth, and the fact that at certain times, the timerequired to implement the various signal processing algorithms induce anobjectionable degree of latency into the bi-directional communication(e.g., conversation).

In an effort to help correct this problem, the CDMA communicationsindustry has adopted various signal encoding/decoding techniques whichcounteract the effects of signal degradation and improve or ensure theintegrity of the information at the receiving device, and signalprocessing techniques which are fast executing to reduce latency. Hence,many digital communications systems available on the market useencoding/decoding methods that are each able to accomplish reasonablecommunication quality under normal operating conditions. However, whilethese encoding/decoding methods help ensure the integrity of thereceived information, they also tend to add a larger than desired amountof latency to communications system as the encoding/decoding algorithmsare processed. Examples include standards such as IS-95A, J-STD-008,TIA/FIA-95-B, etc., which describe the multiplexing an demultiplexingprimary, secondary and signaling traffic to and from an underlyingphysical layer traffic channel in a CDMA system.

Thus, what is needed is a solution which tailors the encoding/decodingtechniques to maximize voice quality of the CDMA communications system.What is required is a method which seamlessly functions with thedynamically adjusting parameters of the encoding/decoding algorithmsutilized in CDMA communications systems. What is required is a solutioncapable of transmitting the required side band data without addingsignificant latency to the voice communications data. In addition, therequired solution should not overly reduce the observed voice signalquality. The present invention provides a novel solution to the aboverequirements.

DISCLOSURE OF THE INVENTION

The present invention provides a solution which tailors theencoding/decoding techniques to maximize voice quality of the CDMAcommunications system. The present invention provides a method andsystem which seamlessly functions with the dynamically adjustingparameters of the encoding/decoding algorithms utilized in CDMAcommunications systems. The present invention provides a solutioncapable of transmitting the required signaling data without addingsignificant latency to the voice communications data and without overlyreducing the observed voice signal quality.

In one embodiment, the present invention is implemented as a CDMAcommunications station in a bidirectional CDMA based wireless digitalcommunications system. The CDMA communications station includes a signalencoder adapted to encode signaling information into a signaling packet.A vocoder (voice encoder) is also included to encode voice informationat a variable data rate and process the voice information into a voicepacket. A multiplexer is coupled to receive the voice packet from thevoice encoder and coupled to receive the signaling packet from thesignal encoder. The multiplexer combines the voice packet and thesignaling packet into a traffic frame. A transmitter is coupled to themultiplexer for transmitting the traffic frame as received from themultiplexer.

An early indication describing the data rate and the size of the voicepacket produced by the voice encoder is generated and provided to themultiplexer. The multiplexer subsequently uses the early data rateindication from the voice encoder to preconfigure the traffic frame forthe variable data rate voice packet. The preconfigured traffic frame isbuilt to readily accept the voice packet once the processing of thevoice packet by the voice encoder is complete. This allows the trafficframe to be sent to the transmitter for transmission immediately uponreception of the voice packet from the voice encoder, thereby reducingthe latency of the digital communications system.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention:

Prior art FIG. 1 shows a general diagram of a typical CDMA digitalcellular system.

FIG. 2 shows a diagram of a CDMA digital cellular mobile station inaccordance with one embodiment of the present invention.

FIG. 3 shows a diagram depicting a multiplexer of a CDMA digitalcellular mobile station in accordance with one embodiment of the presentinvention.

FIG. 4 shows a diagram depicting 4 consecutive traffic frames as outputfrom the multiplexer of FIG. 3 in accordance with one embodiment of thepresent invention.

FIG. 5 shows a diagram of an exemplary 20 ms traffic frame with respectto time in accordance with one embodiment of the present invention.

FIG. 6 shows a flow chart of the steps of a process in accordance with afirst embodiment of the present invention.

FIG. 7 shows a flow chart of the steps of a process in accordance with asecond embodiment of a present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of theinvention, a method and system for using vocoder rate determination forhigh-quality CDMA voice transmission, examples of which are illustratedin the accompanying drawings. While the invention will be described inconjunction with the preferred embodiments, it will be understood thatthey are not intended to limit the invention to these embodiments. Onthe contrary, the invention is intended to cover alternatives,modifications and equivalents, which may be included within the spiritand scope of the invention as defined by the appended claims.Furthermore, in the following detailed description of the presentinvention, numerous specific details are set forth in order to provide athorough understanding of the present invention. However, it will beobvious to one of ordinary skill in the art that the present inventionmay be practiced without these specific details. In other instances,well known methods, procedures, components, and circuits have not beendescribed in detail as not unnecessarily to obscure aspects of thepresent invention.

The present invention provides a solution which tailors theencoding/decoding techniques to maximize voice quality of the CDMAcommunications system. The present invention provides a method andsystem which seamlessly functions with the dynamically adjustingparameters of the encoding/decoding algorithms utilized in CDMAcommunications systems. The present invention provides a solutioncapable of transmitting the required side band data without addingsignificant latency to the voice communications data and without overlyreducing the observed voice signal quality.

Specifically, embodiments of the present invention include multiplexingfunctionality that is coupled to receive an early data rate indicationfrom a voice encoder such that the multiplexing functionality is able topreconfigure itself (e.g., specifically tailor the traffic frame fortransmission) for the variable data rate voice packet to be deliveredonce the processing of the voice packet by the voice encoder iscomplete. This allows the traffic frame to be sent for transmissionimmediately upon reception of the voice packet from the voice encoder,thereby reducing the latency of the digital communications system.Embodiments the present invention are described in greater detail below.

Referring now to FIG. 2, a diagram of a mobile station 200 in accordancewith one embodiment of the present invention is shown. Station 200 istypically implemented as a cell phone. Station 200 is bi-directional, inthat information is both transmitted (e.g., to a base station) via anincluded transmitter 220 and received via an included receiver 221. Asdepicted in FIG. 2, on the transmitter side, station 200 includes avoice encoder 201 coupled to a multiplexer 202. A controller 204 is alsocoupled to multiplexer 202 via a signal encoder 205. The output ofmultiplexer 202 is coupled to a channel codec 203, which is in turncoupled to the transmitter 220. On the receiver side, station 200includes the receiver 221 coupled to a channel codec 213. The output ofchannel codec 213 is coupled to a multiplexer 212. A multiplexer 212 iscoupled to a voice decoder 211, and is also coupled to a controller 214via a signal decoder 215.

In the present embodiment, station 200 implements a mobile CDMAcommunications station in a CDMA based wireless digital communicationssystem. The signal encoder 205 in station 200 is a CDMA based signalencoder adapted to encode signaling information from controller 204 intoa series of signaling packets. Voice encoder 201 functions in part byencoding voice information at a variable data rate and processing thevoice information into a series of voice packets. Multiplexer 202 iscoupled to receive the voice packets from the voice encoder 201 andcoupled to receive the signaling packets from the signal encoder 205.Multiplexer 202 combines the voice packets and the signaling packetsinto a series of “traffic frames” for transmission via channel codec 203and transmitter 220. Channel codec 203 encodes the traffic frames intoCDMA based transmission frames and couples the transmission frames totransmitter 220 for transmission.

In the present embodiment, the operation of multiplexer 202 is inaccordance with well known CDMA protocols (e.g., the multiplex sublayerin IS-95A, J-STD-008, TIA/EIA-95-B, etc.). Multiplexer 202 functions inpart by multiplexing primary, secondary, and signaling traffic tochannel codec 203 and transmitter 220 (e.g., the underlying physicallayer traffic channel).

In the present embodiment, the traffic channel (e.g., the communicationspathway for multiplexer 202 to transmitter 220) itself can be configuredto use up to 4 distinct frame rates. In accordance with CDMA protocols,the traffic channel comprises a series of consecutive 20 ms frames. Asdetermined by the configuration of multiplexer 202 (e.g., the multiplexsublayer in IS-95A, J-STD-008, TIA/EIA-95-B, etc.) up to 4 distinctframe rates are implemented using one of 4 possible frame sizes.Different traffic frame sizes can be implemented in each 20 ms trafficframe, wherein each frame size is associated with a particular voiceencoder 201 data rate. Consecutive 20 ms traffic frames need nottransmit the same size of frame (e.g., amount of data), but rather thesize of the traffic frame can be varied dynamically from frame to frame.The primary reason for this architecture is to support a variable bitrate output of voice encoder 201. During normal operation, voice encoder201 outputs variable size voice packets corresponding to the amount ofvoice information in the incoming voice signal (e.g., mic/line-in). Lowdata rate voice packets (e.g., smaller voice packets) are produced whenless information is present in voice signal, and high data rate voicepackets (e.g., larger) are produced when more information is present.

Referring now to FIG. 3, a diagram depicting multiplexer 202 in greaterdetail is shown. As depicted in FIG. 3, in the present embodiment,multiplexer 202 includes a voice buffer 301 and a signal buffer 302 bothcoupled to an output buffer 303. The buffers 301-303 function byallowing multiplexer 202 to receive incoming voice packets from voiceencoder 201 and receive incoming signaling packets from signal encoder205 and to construct outgoing traffic frames therefrom. As describedabove, in the present embodiment, multiplexer 202 uses the 4 distinctframe rates to transport both the voice data from voice encoder 201 andsignal data from signal encoder 205. Multiplexer 202 makes a dynamicframe by frame determination as to which of the four frame rates will beused (e.g., what size traffic frame will be built) and how much of eachof the logical data type (e.g. voice data, signal data, etc.) will becontained therein. Based upon this determination, voice data from voicebuffer 301 and signal data from signal buffer 302 are combined intotraffic frames within output buffer 303, and are in turn output tochannel codec 203 and transmitter 220 (as shown in FIG. 2).

It should be noted that two aspects of the implementation of multiplexer202 and of the interface between multiplexer 202 and voice encoder 201have a disproportionate effect on the observed voice quality. The firstaspect is the overall latency of station 200, referring to the delayvoice packets experience in reaching a far end communication device (notshown). The second aspect is the degree to which voice packets producedby voice encoder 201 are limited in size because of station 200's needto transmit call control or call maintenance data (e.g., signalingpackets) over the same traffic channel as is used for the voice packets.

The overall latency, or end-to-end delay, experienced by voice packetscan have a significant impact on the perceived “natural” quality of theconversation. In the present embodiment, while the CDMA communicationssystem including station 200 of the present invention has severalinherent delays associated with the signal processing for voice andchannel encoding and decoding, station 200 includes novel features forgreatly reducing the latency experienced by the voice packets.

Referring now to FIG. 4, a diagram 400 showing for consecutive thetraffic frames 401-404 as output from multiplexer 202 is shown. Asdepicted in FIG. 4, each of traffic frames 401-404 include voice dataand signal data, with traffic frames 401-402 also including amounts ofempty space. As depicted in FIG. 4, transmission time is representedalong horizontal axis, and each of frames 401-404 are 20 ms wide.

In the present embodiment, voice encoder 201 makes a decision every 20ms as to the size of voice packet which it will build for transmissionvia the traffic channel to the far end. This decision is based heavilyon the information content of the voice signal (e.g., received frommic/line-in). Higher voice information content in the voice signalrequires larger size voice packets to be built by voice encoder 201.Lower voice information content allows voice encoder 201 to buildsmaller voice packets, which results in power and capacity savings.

For a given traffic frame, if voice encoder 201 is restricted bymultiplexer 202 from building higher-rate voice packets so thatmultiplexer 202 can multiplex greater amounts of signaling packets intothe traffic frame, and if voice encoder 201 would otherwise have madethe decision to generate and send a high rate voice packet due to highvoice information content of voice signal, then the observed voicequality will be necessarily reduced. This is graphically depicted indiagram 400 by traffic frames 401 and 402 which are not spaceconstrained (e.g., where they both include empty space), as opposed totraffic frames 403 and 404.

In accordance with the present invention, multiplexer 202 is coupled toreceive an early voice data rate indication from the voice encoder suchthat the multiplexer 202 is able to preconfigure the traffic frame forthe variable data rate voice packet to be delivered once the processingof the voice encoder is complete. This allows the traffic frame to besent by multiplexer 202 to the channel codec 203 and transmitter 220 fortransmission immediately upon reception of the voice packet from thevoice encoder, thereby reducing the overall latency and improving theobserved voice quality of the communications system.

Referring now to FIG. 5, a diagram of an exemplary 20 ms traffic frame500 with respect to time (e.g., shown along the horizontal axis) inaccordance with one embodiment the present invention is shown.

A first embodiment of the present invention increases observed voicequality by minimizing the latency in transmission of voice packets bytaking advantage of an aspect of the variable data rate ability of voiceencoder 201 wherein voice encoder 201 provides an early indication tomultiplexer 202 as to the size of voice packet which it is generating.As described above, voice encoder 201 builds the variable size voicepacket for inclusion in each 20 ms traffic frame, in this case, trafficframe 500.

In this embodiment, voice encoder 201 functions by first performing avocoder rate, or data rate, determination phase which determines thesize of voice packet to be built, followed by an analysis/synthesisphase during which the voice packet is actually constructed. Inaccordance with present invention, voice encoder 201 informs multiplexer202 of the voice packet size as soon as the vocoder rate determinationphase is complete. This early indication allows the multiplex sublayer(e.g., multiplexer 202) sufficient time to fully prepare traffic frame500 for transmission within its current 20 ms time duration. By takinginto consideration the size of the voice packet which will be deliveredonce analysis/synthesis is complete and the amount of signaling datawhich can be included, the multiplex sublayer functionality prepares allother portions of the traffic frame (e.g., signal data, etc.) whilevoice encoder 201 is completing the voice packet construction. Once thevoice packet construction is complete, the voice packet is delivered tomultiplexer 202 and inserted into a “reserved portion” of the trafficframe (e.g., traffic frame 500). Traffic frame 500 is then complete andis delivered to channel codec 203 for coding and transmission viatransmitter 220. All of this takes place within the same 20 ms voiceencoder time duration corresponding to the 20 ms time duration oftraffic frame 500. In this manner, additional delays due to theoperation of the multiplex sublayer functionality are not incurred. Inaccordance with the present embodiment, the voice packet is delivered tothe channel codec 203 essentially as soon as it has been built by voiceencoder 201.

FIG. 6 shows a flow chart of the steps of a process 600 in accordancewith one embodiment of the present invention. As depicted in FIG. 6,process 600 shows the operating steps of the voice rate determination,encoding, and transmission process of a station (e.g., station 200) inaccordance with the present invention.

Process 600 begins in step 601, where a voice encoder (e.g., voiceencoder 201 of FIG. 2) in accordance with one embodiment of the presentinvention receives voice information from a voice signal source fortransmission to a far-end device.

In step 602, voice encoder 201 performs vocoder rate determination onthe voice signal to determine a data rate and a voice packet sizecorresponding to the information content of the voice signal. Asdescribed above, the information content of the voice signal varies withtime. At some instances, more data is required to properly represent thevoice information content than at other instances. Accordingly, the sizeof the voice packets built by the voice encoder 201 varycorrespondingly.

In step 603, voice encoder 201 provides an early indication tomultiplexer 202 regarding the data rate for the voice information in thevoice signal. As described above, this early indication allows themultiplex sublayer (e.g., multiplexer 202) sufficient time to fullyconfigure and prepare a traffic frame for transmission within thetraffic frame's current 20 ms time duration.

In step 604, multiplexer 202 prepares a traffic frame for transmission.As described above, this traffic frame is configured based upon theearly indication of the data rate received from the voice encoder 201.

In step 605, the voice packet from the voice encoder 201 is received bymultiplexer 202 and is incorporated into the preconfigured trafficframe.

Hence, in step 606, the complete traffic frame is output by multiplexer202 to a coupled channel codec 203 and transmitter 220 for transmissionvia the traffic channel. As described above, steps 602-606 take placewithin the same 20 ms voice encoder time duration corresponding to the20 ms time duration of the traffic frame such that additional delays dueto the operation of the multiplex sublayer functionality are notincurred.

With reference once again to FIG. 5, a second embodiment of the presentinvention increases observed voice quality by minimizing those occasionswhere the size of the voice packets produced by encoder 201 areconstrained by the multiplex sublayer functionality, due to, forexample, the need to transmit large amounts of signal data. This secondembodiment maximizes voice quality by implementing the multiplexsublayer functionality in such a way as to opportunistically wait forvoice encoder 201 to transmit a “less-than-full-rate” voice packet(e.g., a smaller voice packet) rather than force the voice encoder 201to a lower data rate when multiplexer 202 has signaling data to send. Inthis embodiment, multiplexer 202 attempts to take advantage of thenaturally occurring lower-rate voice packets to deliver signalingpackets, and thereby minimize the negative effect which signalingtraffic might otherwise have on voice quality (e.g., those occasionswhere large amounts of signal traffic necessitate discarding excessiveamounts of voice information). The signaling packets are buffered (e.g.,in signal buffer 302 shown in FIG. 3) until appropriate transmissionopportunities arise. In so doing, the data rate of the voice encoder 201is not artificially constrained by the signaling requirements of station200.

It should be appreciated, however, that there may exist circumstanceswherein multiplexer 202 must resort to constraining the bit rate ofvoice encoder 201 if the opportunity to send signaling information doesnot naturally occur within some period of time. In such situations,multiplexer 202 constrains the size of the voice packets generated byvoice encoder 201 in order to allow the transmission of the signalingdata. In such situations, the constraining of the bit rate of voiceencoder 201 by multiplexer 202 is used as a fallback mechanism to ensureneeded signal data is not starved of traffic channel bandwidth.

FIG. 7 shows a flow chart of the steps of a process 700 in accordancewith the second embodiment of a present invention. As depicted in FIG.7, process 700 shows the steps of the operating process of a station 200in accordance with the second embodiment of present invention describedabove, wherein the occasions where the size of the voice packetsproduced by voice encoder 201 are constrained by the multiplex sublayerfunctionality are minimized.

Process 700 begins in step 701, where a voice encoder (e.g., voiceencoder 201 of FIG. 2) in accordance with one embodiment of the presentinvention receives voice information from a voice signal source fortransmission to a far-end device.

In step 702, the voice information of the voice signal is encoded intovoice packets having respective sizes (e.g., data rates) correspondingto the voice information contained in the voice signal.

In step 703, the resulting voice packets are output to the coupled tomultiplexer 202.

In step 704, multiplexer 202 receives signal data packets fortransmission via the traffic channel.

In step 705, multiplexer 202 buffers the signaling packets forincorporation into traffic frames having low data rate voice packets. Asdescribed above, multiplexer 202 includes a buffer (e.g., signal buffer302 shown in FIG. 3) for temporarily storing signaling packets for laterincorporation into a traffic frame. As described above, multiplexer 202opportunistically waits for voice encoder 201 to transmit a“less-than-full-rate” voice packet (e.g., a smaller voice packet) inorder to incorporate signal data packets into the traffic frames ratherthan force the voice encoder 201 to a lower data rate when multiplexer202 has signaling data to send.

In step 706, the traffic frames are built by multiplexer 202 using thebuffered signal data and the outgoing low data rate voice packets.

Subsequently, in step 707, multiplexer 202 outputs the resulting trafficframes to channel codec 203 and transmitter 220 for transmission. Inthis manner, process 700 takes advantage of the naturally occurringlower data rate voice packets to deliver signaling packets, and therebyminimize the negative effect which signaling traffic might otherwisehave on voice quality.

Thus, the present invention provides a solution which tailors theencoding/decoding techniques to maximize voice quality of the CDMAcommunications system. The present invention provides a method andsystem which seamlessly functions with the dynamically adjustingparameters of the encoding/decoding algorithms utilized in CDMAcommunications systems. The present invention provides a solutioncapable of transmitting the required side band data without addingsignificant latency to the voice communications data and without overlyreducing the observed voice signal quality.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order best toexplain the principles of the invention and its practical application,thereby to enable others skilled in the art best to utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

What is claimed is:
 1. In a CDMA based wireless digital communicationssystem, a CDMA communications station comprising: a signal encoderadapted to encode signaling information into a signaling packet; a voiceencoder adapted to encode voice information and process the voiceinformation into a voice packet; a multiplexer coupled to receive thevoice packet and coupled to receive the signaling packet and forcombining the voice packet and the signaling packet into a trafficframe; and a transmitter coupled to the multiplexer for transmitting thetraffic frame as received from the multiplexer; the multiplexer furthercoupled to receive an early data rate indication from the voice encodersuch that the multiplexer preconfigures the traffic frame for the voicepacket prior to receiving the voice packet from the voice encoder suchthat the traffic frame is sent to the transmitter for transmission uponreception of the voice packet from the voice encoder, thereby reducingthe latency of the digital communications system.
 2. The CDMAcommunications station of claim 1 wherein the voice encoder is adaptedto process the voice information into the voice packet using a variabledata rate, and wherein the variable data rate results in a variable sizeof the voice packet.
 3. The CDMA communications station of claim 2wherein the variable size of the voice packet is described by the earlyindication, enabling the multiplexer to preconfigure the traffic framefor the variable size of the voice packet.
 4. The CDMA communicationsstation of claim 1 wherein the signaling information includes controldata for controlling communications with the CDMA communicationsstation.
 5. The CDMA communications station of claim 1 further includinga channel codec coupled between the multiplexer and the transmitter forencoding the traffic frame onto a traffic channel in accordance withCDMA protocols.
 6. The CDMA communications station of claim 1, whereinthe multiplexer is configured to build traffic frames 20 ms in length bycombining the voice packet and the signaling packet.
 7. The CDMAcommunications station of claim 6 wherein the early indication allowsthe multiplexer to build the signaling information into the trafficframe while reserving a proper amount of space in the traffic frame forthe voice packet described by the early indication.
 8. A mobile CDMA(code division multiple access) communications station in a CDMA basedwireless digital communications system, comprising: a signal encoderadapted to encode signaling information from a coupled controller into asignaling packet; a voice encoder adapted to encode voice informationand process the voice information into a voice packet, wherein the voiceencoder is adapted to process the voice information using a variabledata rate, the variable data rate resulting in a variable size of thevoice packet; a multiplexer coupled to receive the voice packet andcoupled to receive the signaling packet and for combining the voicepacket and the signaling packet into a traffic frame; and a transmittercoupled to the multiplexer for transmitting the traffic frame asreceived from the multiplexer; the multiplexer further coupled toreceive an early data rate indication from the voice encoder such thatthe multiplexer preconfigures the traffic frame for the voice packetprior to receiving the voice packet from the voice encoder such that thetraffic frame is sent to the transmitter for transmission upon receptionof the voice packet from the voice encoder, thereby reducing the latencyof the digital communications system.
 9. The CDMA communications stationof claim 8 wherein the variable size of the voice packet is described bythe early indication, enabling the multiplexer to preconfigure thetraffic frame for the variable size of the voice packet.
 10. The CDMAcommunications station of claim 8 wherein the signaling informationincludes control data for controlling communications with the CDMAcommunications station.
 11. The CDMA communications station of claim 8further including a channel codec coupled between the multiplexer andthe transmitter for encoding the traffic frame onto a traffic channel inaccordance with CDMA protocols.
 12. The CDMA communications station ofclaim 8, wherein the multiplexer is configured to build traffic frames20 ms in length by combining the voice packets and the signaling packet.13. The CDMA communications station of claim 12 wherein the earlyindication allows the multiplexer to build the signaling informationinto the traffic frame while reserving a proper amount of space in thetraffic frame for the voice packet described by the early indication.14. In a CDMA (code division multiple access) communications station, amethod for low latency voice encoding and transmission, the methodcomprising the steps of: a) receiving voice information at a voiceencoder for transmission from a voice signal source; b) performing ratedetermination on the voice signal to determine a data rate and a voicepacket size corresponding to the voice information in the voice signal;c) providing an early indication signal describing the size of the voicepacket to a multiplexer coupled to the voice encoder; d) preparing atraffic frame using the multiplexer, wherein the traffic frame includessignaling information from a signal encoder coupled to the multiplexer;e) configuring the traffic frame to accept the voice packet prior toreceiving the voice packet in the multiplexer by using the earlyindication, thereby reducing latency incurred in building the trafficframe; f) receiving the voice packet at the multiplexer andincorporating the voice packet into the traffic frame; and g) outputtingthe traffic frame from the multiplexer to a coupled transmitter fortransmission.
 15. The method of claim 14 wherein the voice encoder isadapted to process the voice information into the voice packet using avariable data rate, and wherein the variable data rate results in avariable size of the voice packet.
 16. The method of claim 15 whereinthe variable size of the voice packet is described by the earlyindication, enabling the multiplexer to preconfigure the traffic framefor the variable size of the voice packet.
 17. The method of claim 14wherein the signaling information includes control data for controllingcommunications with the CDMA communications station.
 18. The method ofclaim 14 further including a channel codec coupled between themultiplexer and the transmitter for encoding the traffic frame onto atraffic channel in accordance with CDMA protocols.
 19. The method ofclaim 14 wherein the multiplexer is configured to build traffic frames20 ms in length by combining the voice packet and the signaling packet.20. The method of claim 19 wherein the early indication allows themultiplexer to build the signaling information into the traffic framewhile reserving a proper amount of space in the traffic frame for thevoice packet described by the early indication.